|Year : 2010 | Volume
| Issue : 3 | Page : 173-178
Relative position of the mandibular foramen in different age groups of children: A radiographic study
KS Poonacha1, AL Shigli2, KR Indushekar3
1 Senior Lecturer, K.M. Shah Dental College and Hospital, Sumandeep Vidyapeeth University, Waghodia Road, Vadodara, Gujarat, India
2 Professor and Head, Modern Dental College and Hospital, Indore, Madhya Pradesh, India
3 Director P.G. Studies, Sudha Rustagi College of Dental Sciences and Research, Faridabad, Haryana, India
|Date of Web Publication||11-Dec-2010|
K S Poonacha
Senior Lecturer, K.M. Shah Dental College and Hospital, Pipariya, Waghodia Road, Vadodara Dist., Gujarat - 391 760
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objectives: To assess the relative position of the mandibular foramen (MF) and to evaluate the measurement of gonial angle (GoA) and its relationship with distances between different mandibular borders in growing children between 3 and 13years of dental age. Materials and methods: The radiographs were traced to arrive at six linear and two angular measurements from which the relative position of the MF was assessed and compared in different age groups to determine the growth pattern of the mandible and changes in the location of the MF. Results: The distances between the MF and the anterior plane of the ramus were greater than that between MF and posterior plane of the ramus through all stages. There was a maximum increase in the vertical dimensions of the mandible compared with the horizontal dimensions, particularly in the late mixed dentition period. Conclusion: The mandible and its growth did not alter the position of the MF, both vertically and horizontally, in relation to different landmarks, and more obtuse GoA indicated an increased growth potential of the mandible. This has major implications in the inferior alveolar nerve block technique when used in children.
Keywords: Gonial angle, inferior alveolar nerve block, local anesthesia, mandibular foramen
|How to cite this article:|
Poonacha K S, Shigli A L, Indushekar K R. Relative position of the mandibular foramen in different age groups of children: A radiographic study. J Indian Soc Pedod Prev Dent 2010;28:173-8
|How to cite this URL:|
Poonacha K S, Shigli A L, Indushekar K R. Relative position of the mandibular foramen in different age groups of children: A radiographic study. J Indian Soc Pedod Prev Dent [serial online] 2010 [cited 2020 Feb 29];28:173-8. Available from: http://www.jisppd.com/text.asp?2010/28/3/173/73798
| Introduction|| |
Successful anesthesia of the mandibular arch is difficult to accomplish in children.  Two major factors are involved in the failure of inferior alveolar nerve block (IANB): the first is accessory innervations and the second, and most common, is improper placement of needle because of improper evaluation of landmarks. 
Pedodontists could enjoy greater success if the location of MF could be determined at various age intervals. Although there have been many studies evaluating the location of MF in adults, the positional changes in growing children, however, have rarely been reported. ,,,,,, Therefore, this study was undertaken to evaluate the relative position of the mandibular foramen (MF) and also the changes in the gonial angle (GoA).
| Materials and Methods|| |
The study was performed in 180 children in the age group of 3-13 years. The children were divided into six groups based on the Hellman's dental developmental stages, with 30 children in each of the categories: (1) IIA, (2) IIC, (3) IIIA, (4) IIIB, (5) IIIC and (6) IVA [Table 1]. 
Children with previous orofacial trauma, surgery, Temporomandibular joint and craniocervical disorders and those falling under Hellman's stages of IA, IC, IVC and VA were excluded as they did not fit into the age group selected.
|Table 1: Division of samples into Hellman's dental developmental stages based on dental age and clinical findings |
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The standardized radiographic procedure was fully explained to the parents/children. A dry run was made before each exposure to demonstrate the machine by cycling and all safety precautions were exercised. Constant voice contact with the subject was maintained to provide security to the young patient.
A panoramic radiographic machine (Rotograph 230 EUR, Villa medical systems, Italy) was used with a Kodak Lanex cassette and Kodak T-MAT G films to obtain the orthopantamographs (OPGs). The left side of the outline of the mandible on each radiograph was traced on the matte acetate paper. Various landmarks were mentioned as reference points [Figure 1] and were connected to form different planes and angles [Figure 2].
|Figure 1: Reference points and planes. Point -1: Center of the MF. Point -2: Most prominent point on the anterior border of the ramus. Point -3: Deepest point on the anterior border of the ramus. Point -4: Intersecting point of the perpendicular line from the MF to P1. Point -5: Intersecting point of P1 and P3. Point -6: The distal alveolar crest of the most distal molar. Point -7: Mesial alveolar crest of the canine. Point -8: Most prominent posterior point of the condyle. Point -9: Intersecting point of the perpendicular line from the MF to P2. Point -10: Most prominent posterior point at the angle of mandible. Point -11: Intersecting point of P2 and P4. Point -12: Intersecting point of the perpendicular line from the MF to P4. Point -13: Most prominent inferior point at the angle of mandible. Point -14: Most prominent inferior point at the canine area. Plane 1 - (P1): Plane connecting reference points 2 and 3 (ramus anterior plane). Plane 2 - (P2): Plane connecting reference points 8 and 10 (ramus posterior plane). Plane 3 - (P3): Plane connecting reference points 6 and 7 (alveolar crest plane). Plane 4 - (P4): Plane connecting reference points 13 and 14 (mandibular plane).|
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|Figure 2: Linear and angular measurements between reference points and planes. L1: Distance between reference points 1 and 4 (Linear horizontal measurement). L2: Distance between reference points 1 and 9 (Linear horizontal measurement). L3: Distance between reference points 4 and 5 (Linear vertical measurement). L4: Distance between reference points 9 and 11 (Linear vertical measurement). L5: Distance between reference points 5 and 11 (Linear vertical measurement). L6: Distance between reference points 1 and 12 (Linear vertical measurement). A1: Angle between planes P1 and P3 (Angular measurement). A2: Angle between planes P2 and P4 (Angular measurement)|
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In each of the radiographs, six linear measurements, i.e. two horizontal (L1 and L2) and four vertical (L3, L4, L5 and L6), were made using digimatic calipers with 0.01 mm precision. Two angular measurements on the GoA were made using the protractor. All the obtained data were then summarized in the form of tables for each of stages.
To check for the intraexaminer reliability, a total of 30 samples (five from each group) were selected randomly. The landmarks were identified, traced and measured. The same samples were retraced and measured after a gap of 2 weeks and the values were compared using the unpaired t-test. The results showed no significant difference in all the measurements and hence the study was continued on all the samples.
The mean values and the standard deviations of linear and angular measurements in each of the Hellman's stage were calculated. One-way analysis of variance was used for comparison of values [Table 2] and [Table 3]. Karl Pearson's correlation coefficient test was performed [Table 4]. Significance of the values was tested through unpaired t-test at P <0.05. All the analyses were performed using SPSS statistical software package.
|Table 2: The mean values and standard deviations of linear measurements in each stage and the results of analysis of variance |
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|Table 3: The mean values and standard deviations of angular measurements in each stage and the results of analysis of variance |
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The relative position of the MF was then arrived at by comparing the dimensions of each of the linear and angular measurements as all of them were interconnected and showed complementary increase or decrease in values with growth.
| Results|| |
Overall, the linear measurements showed an increase in values with age, except in the mean values of L3, which varied a lot between each of the stages and was inconsistent.
Statistically, there were no significant differences between the mean values of the linear horizontal measurements (L1 and L2) among the six stages in both mandibular anterior border to MF and MF to mandibular posterior border, but significant differences between the mean values of all the vertical linear measurements (L3, L4, L5 and L6) were seen among the six stages [Table 2]. Statistically, there were no significant differences between the mean values of both the angular measurements among the six stages; however, overall, the angular measurements showed a decrease in the values with age, except an increase in mean values in A1 between the adjacent stages IIA and IIC and in A2 between the adjacent stages IIIA and IIIB [Table 3].
Karl Pearson's correlation coefficient test showed that, overall, there were significant positive correlations with linear measurements except between L2 and L3 and between L2 and L4, which were not significant, although positive. There were also negative correlations between some linear measurements that were not significant, except between L3 and L5, which showed significance. Overall, the linear and angular measurements showed negative correlation with high significance. There were some positive correlations between some linear and angular measurements, but these were not significant. The correlation between the angular measurements A1 and A2 was positive and significant [Table 4].
| Discussion|| |
The mandible is in a constant phase of remodeling as the child grows. It shows a differential growth pattern and remodeling at different areas. The eruption and shedding process of the teeth plays an important role in bone remodeling, particularly at the anterior border of the ramus and the alveolar crestal plane, which may influence the position of MF and, hence, the IANB procedure. The provision of the dental treatment depends on achieving excellent local anesthesia (LA). Pain-free treatment procedures are of obvious benefit both to the patient and to the operator, as treatment can be performed in a calm, unhurried fashion.
Technical errors of positioning the needle too high, too low, superficially or intravascularly also contribute to missed blocks.  The Gow-Gates and Akinosi methods are best reserved for those cases where the conventional block methods fail as they can produce more complications than the standard approach. 
An OPG may help in locating the position of the MF.  OPGs showed negligible distortion of ramus length , and are a useful tool for measuring GoA, which is an indicator of mandibular steepness and, subsequently, mandibular growth directions.  Also, no significant difference has been found between OPGs and oblique cephalometric radiographs in determining the location of MF. 
Different studies have shown different positions of the MF, just posterior to the middle of the ramus, , posterior to the middle of the ramus in the third quadrant,  at the midpoint,  about three-fourths of the distance from the anterior border,  approximately at the posterior third of the ramus in both vertical and horizontal directions,  vertically at the occlusal plane in children and no age-related difference in the anteroposterior position of the MF,  inferior to the occlusal plane,  midway and slightly inferior to the line connecting the deepest concavity on the internal oblique ridge and posterior border of ramus.  However, most of the studies carried out previously were on adult mandibles.
Studies have shown that there is no difference between male and female values with regard to discerning the MF locale,  and also there is no right and left side dominance in the ramus and MF; , therefore, in this study, data from both the genders were pooled and only the left side of the mandible was traced, but both sides of the mandible were considered to determine the dental age of the patient clinically.
The results of the present study showed that the distance between the MF and the ramus anterior plane (L1) was greater than that between the MF and the ramus posterior plane (L2) through all stages and that the MF was consistently located in the posterior part of the middle third of the ramus. The results also reveal that the growth rate of the ramus anterior border declined till the exchange phase of the lateral teeth, showing a growth spurt after that, whereas the growth of the ramus posterior border showed a gradual decline in growth rate till the eruption phase of the permanent second molar and then a slight increase in growth rate after that, indicating that the growth of the ramus posterior border is more predictable and consistent compared with the growth of the ramus anterior border, which showed least growth during the exchange phase of the lateral teeth and increase in deposition of bone after that.
In the vertical direction, the distance from the MF level to the alveolar crest plane changed little from stage IIA to IVA and showed both increase and decrease in values, suggestive of the constant remodeling of bone at the alveolar crest plane due to active phase of eruption and shedding. The remodeling process at the anterior border of the ramus could also influence this. It also indicates that the vertical position of the MF is relatively constant from the alveolar crestal plane in spite of the significant increase in the vertical dimensions of the mandible. Although L3 could not be specifically used to arrive at the vertical position of the MF from the occlusal plane but, considering the crown height of the teeth, it can be roughly said that the MF lies near the occlusal plane in all the stages.
The distance from the MF to the mandibular lower border showed a significant increase from stage IIA to IVA. In the vertical direction, the mandible developed more in the late mixed dentition stage. There was constant decrease in GoA A2 from stage IIA to IVA and slight increase between stage IIIA and IIIB, which were not significant. Overall, the GoA had a negative correlation with distances between the MF and each mandibular border, which was in agreement with a similar study by Tsai. 
If the inferior alveolar neurovascular triad is considered to be a soft tissue matrix, the mandible and its growth will not alter the position of the matrix.  The results of this study go well with this observation and compliment the functional matrix theory of Moss, which states that the growth of the skeletal unit is secondary to the primary changes in specific functional matrices. In this case, it is the MF and its contents that influence the growth of the mandible, and the growth of the mandible may not change the position of the MF. 
We have used different landmarks to arrive at the position of the MF. Therefore, the position of the MF is only relative. There were not many age-related changes in the relative position of the MF, particularly anterio-posteriorly and from the alveolar crestal plane, although there were differences in the bone-remodeling rate at different borders. Going by the findings of this study and applying it clinically, we have found a good success rate during the IANB technique by placing the needle at the occlusal level in all age groups studied and entering the oral cavity from the canine region of the opposite side.
A similar study was conducted to determine the relative position of the MF in different age groups,  but there is no Indian study that locates the MF in different age groups. The present study sample consisted only of the south Indian population; however, various other parameters may play a role, like the ethnic and racial variations in the jaw growth patterns, the accuracy of the radiographic machine, the magnification factors, proper patient positioning, identification of the landmarks on radiographs and, finally, identification of the landmarks intraorally during IANB, which are highly individualistic. Therefore, similar studies may have to be conducted on large population groups with proper calibration of the examiners before arriving at any final conclusion.
| Acknowledgments|| |
The authors are grateful to Dr. Dayanand Shirol, Dr. Shivayogi M. Hugar, Dr. Varun Sardana, Dr. Ravindranath Reddy, Dr. Roshan N. M., Dr. Santosh Sholapurmath, Dr. Arun Rathnam and Dr. Nidhi Madan for their help in conducting the study.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]
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